The present invention relates to a mechanical key code verification system for use with a mechanical key having a key code pattern of recessed portions and non-recessed portions and including a lock apparatus that mechanically verifies the key code pattern.
In the prior art, various types of key systems are used to prevent unauthorized use of articles, doors, and the like by a third person. A typical key system uses a key that includes a grip and an elongated key plate (also referred to as a key blade), which has an engraved key code. Insertion of the key plate into a cylinder of a lock apparatus aligns the engraved key code with a plurality of disk tumblers (small steel pieces), which are biased by springs arranged in the cylinder. Rotation of the cylinder with the key is permitted when the key code of the key plate matches a key shape formed by the disk tumblers. In such a case, the opening and closing of the lock apparatus is enabled. Japanese Utility Model Registration No. 3090369 (patent document 1) and Japanese Laid-Open Patent Publication No. 2004-76375 (patent document 2) describe examples of a card key system using a card key. FIG. 10 illustrates a card key system 81. The card key system 81 includes a card key 82 and a lock apparatus 86. The card key 82 has a key code pattern 83 including a plurality of holes 84 arranged in accordance with a key code of the card key 82.
FIG. 11 illustrates the lock apparatus 86 (also referred to as a fixed component) in a state in which the card key 82 is not inserted therein. The lock apparatus 86 includes a supporting member 90 and a movable member 88 supported by the supporting member 90. The movable member 88 moves relative to the supporting member 90 when the card key 82 is inserted into the lock apparatus 86 to perform a key operation. The movable member 88 and the supporting member 90 may be referred to as the movable side and fixed side, respectively. A plurality of pin tumblers 87 are arranged so as to extend into the movable member 88 and the supporting member 90. Each pin tumbler 87 includes a lock pin 89 accommodated in the movable member 88 and a plunger pin 91 accommodated in the supporting member 90. The plunger pin 91 is biased towards the lock pin 89 by a tumbler spring 92. The plurality of pin tumblers 87 include first pin tumblers 87a and second pin tumblers 87b. In each first pin tumbler 87a, the plunger pin 91 is engaged with both of the movable member 88 and the supporting member 90 when the card key 82 is not inserted into the lock apparatus 86. In each second pin tumbler 87b, a shear line between the lock pin 89 and the plunger pin 91 is aligned with a shear line between the movable member 88 and the supporting member 90 when the card key 82 is not inserted into the lock apparatus 86.
As illustrated in FIG. 13, when the proper card key 82 is inserted into the lock apparatus 86, the shear line between the lock pin 89 and the plunger pin 91 is aligned with the shear line between the movable member 88 and the supporting member 90 in each of the pin tumblers 87 (first pin tumblers 87a and second pin tumblers 87b). This permits movement of the movable member 88 with respect to the supporting member 90 so that closing and opening of the lock apparatus 86 becomes possible.
As illustrated in FIG. 12, if the card key 82 inserted into the lock apparatus 86 is an improper key, the holes 84 of the card key 82 may be aligned with the first pin tumblers 87a, and the second pin tumblers 87b may be aligned with non-hold portions 85 of the card key 82. In such a first pin tumbler 87a, the plunger pin 91 may be lowered by the amount the distal end of the lock pin 89 is accommodated in the hole 84. Thus, the plunger pin 91 would be engaged with both of the movable member 88 and the supporting member 90. In such a second pin tumbler 87b, the distal end of the lock pin 89 may be lifted by the non-hold portion 85 of the card key 82. Thus, the lock pin 89 would be engaged with both of the movable member 88 and the supporting member 90. As a result, the pin tumblers 87 prohibit movement of the movable member 88 relative to the supporting member 90. Thus, the opening and closing of the lock apparatus 86 cannot be performed with an improper key.    [Patent Document 1] Japanese Utility Model Registration No. 3090369    [Patent Document 2] Japanese Laid-Open Patent Publication No. 2004-76375